This invention relates to a calendar watch with a date ring, and more particularly to an improved mechanism for manually correcting the date shown on the date ring in months having less than 31 days.
Calendar watches and day/date watches are known which incorporate wheels or rings showing the calendar date or day of the week through a small window or windows in the dial of the watch. These wheels or rings are periodically advanced by suitable wheels or levers actuated by the timekeeping mechanism. One such typical prior art device is fully described in U.S. Pat. No. 3,859,783 issued Jan. 14, 1975 to Paul Wuthrich, the present inventor, and assigned to the present assignee. The Wuthrich patent, which is incorporated herein by reference, includes a wheel with upstanding tabs driving both the day dial and the date ring.
A problem encountered in calendar watches with rings having 31 days on the ring is that it is necessary at the end of a month having fewer than 31 days to correct or manually advance the date ring. The date correction mechanism should preferably be simple and fast to operate, but constructed so that it does not interfere with the normal day-to-day date advancing mechanism. Many such arrangements have been shown over the years in the prior art, the following list of patents illustrating mechanisms which are exemplary of the prior art and not intended to be all-inclusive:
______________________________________ U.S. Pat. No. Inventor Issue Date ______________________________________ 3,597,917 Odagiri August 10, 1971 3,645,086 Niznik February 29, 1972 3,659,413 Tanaka et al May 2, 1972 3,683,614 Komiyama August 15, 1972 4,060,977 Rochat December 6, 1977 4,109,458 Suzuki et al August 29, 1978 2,456,122 Guilden December 14, 1948 ______________________________________
Some of the foregoing patents illustrate extremely complicated mechanisms. Others effect the date advance during the manual actuation part of the cycle with the actuator being returned by a spring. This lends itself to the possibility of damage by overenthusiastic actuation of the mechanism. It is more desirable that the advancing step be under the control of a uniform spring return mechanism.
One calendar correction mechanism of this latter type which effects a date advance during the spring-return portion of the cycle rather than during the actuator portion of the cycle is illustrated in U.S. Pat. No. 3,413,800--Dubois et al issued Dec. 3, 1968. The Dubois et al patent incorporates a pivotable date advance lever, one end of which is actuated by a separate lever and having a separate spring member to hold the date advance lever in the proper position. It would be desirable to reduce the complexity of a calendar correction mechanism by incorporating a single piece date advance lever with integral spring biasing portions and having a very simple construction.
Accordingly, one object of the present invention is to provide an improved manual date advance mechanism for a watch which provides for rapid advance of the date ring under control of a spring action after release of a manual actuator.
Another object of the invention is to provide an improved date change lever for such a mechanism having integral spring portions and of simple construction.